Study On The Characteristics Of Early Microvascular Damage In Diabetic Kidney Disease

Part Ⅰ:The diagnostic value of contrast-enhanced ultrasound in the early detection of diabetic kidney diseaseObjective:This study aimed to investigate the diagnostic value of quantitative contrast-enhanced ultrasound(CEUS)for early detection of renal hyperperfusion in diabetic kidney disease(DKD).Methods:65 DKD patients with estimated glomerular filtration rate(eGFR)>30 ml/min/1.73 m2 and 26 normal controls(NCs)were enrolled.Clinical data was well documented.Blood samples were drawn for evaluation of renal function including blood urea nitrogen(BUN),serum creatinine(SCr)and serum uric acid(SUA),and urine samples were assayed for total protein quantification and various microprotein markers.According to eGFR level,DKD patients were divided into early-stage DKD(eGFR≥ 90 ml/min/1.73 m2,n=28)and middle-stage DKD(eGFR 30-90 ml/min/1.73 m2,n=37).Based on urinary microalbumin/creatinine ratio(MALB/UCR),early-stage DKD patients were further classified into two groups:MALB/UCR<10 g/mol(n=13)and MALB/UCR≥10 g/mol(n=15).Kidney biopsy was performed in 11 patients with DKD.Then,CEUS was performed to observe the real-time renal perfusion,and low acoustic power contrast-specific imaging was used for quantitative analysis.Results:The renal perfusion images of CEUS were well developed successively.The corresponding perfusion curves based on echo-power signals in time series were constructed.Quantitative analysis showed that area under the descending curve(AUC2)was significantly increased in early-stage DKD compared to middle-stage DKD(p<0.05),but area under the perfusion curve(AUC)showed no significant difference.Further comparison between different MALB/UCR levels of early-stage DKD showed that patients with MALB/UCR≥10 g/mol had significantly increased levels of AUC,AUC2 and proteinuria than patients with low MALB/UCR(p<0.05).Also,high MALB/UCR DKD patients had increased proteinuria but similar eGFR compared to low MALB/UCR patients.Conclusion:Renal microvascular hyperperfusion may be responsible for overt proteinuria until decline of renal filtration in DKD.AUC2 could be an early and sensitive marker for early renal injury in DKD.Part Ⅱ:The relationship between serum uric acid and renal microvascular perfusion in diabetic kidney diseaseObjective:This study aimed to investigate the relationship between uric acid and renal microvascular perfusion in diabetic kidney disease(DKD)using contrast-enhanced ultrasound(CEUS)method.Methods:79 DKD patients and 26 healthy volunteers were enrolled.Renal function and urine protein markers were tested.DKD patients were subdivided into two groups including a normal serum uric acid(SUA)group and a high SUA group.Contrast-enhanced ultrasound(CEUS)was performed,and low acoustic power contrast-specific imaging was used for quantitative analysis.Results:Normal controls(NCs)had the highest levels of area under the perfusion curve(AUC),area under the ascending curve(AUC1),and area under the descending curve(AUC2).Compared to the normal SUA DKD group,high SUA DKD patients had significantly higher maximum intensity(IMAX),AUC,and AUC1(p<0.05).DKD patients with low urinary uric acid(UUA)excretion had significantly higher AUC2 compared to DKD patients with normal UUA(p<0.05).Conclusion:Hyperuricemia in DKD patients was associated with a renal ultrasound image suggestive of microvascular hyperperfusion.The CEUS parameter AUC1 holds promise as an indicator for renal microvascular hyperperfusion,while AUC2 might be a useful indicator of declining glomerular filtration rate in DKD patients with decreased excretion of uric acid.